ERROR: While executing gem ... (Errno::EPERM) Operation not permitted - /usr/bin/pod

使用如下命令安装cocoa pods

sudo gem install cocoapods

遇到如下错误：

ERROR:  While executing gem ... (Errno::EPERM)     Operation not permitted - /usr/bin/pod

解决办法，改使用下面的命令：

sudo gem install -n /usr/local/bin cocoapods

若想安装指定版本号的cocoapods，请使用如下命令：

sudo gem install -n /usr/local/bin cocoapods -v 0.39.0